1. Field of the Invention
The present invention generally relates to a process and image formation apparatus for feeding paper during the formation of images upon printable media, and, more particularly, to a a process and apparatus that endeavors to minimize errors and interruption of image formation by controlling a pickup roller in an effort to continue to attempt to pick up the printable media when the pickup roller fails to pickup the printable media to be printed.
2. Description of the Related Art
Generally, image formation equipment such as a facsimile apparatus, a copier, a printer or a MFP (e.g., a multi-function peripheral) are products which are commonly manufactured to have a printing function. These machines are equipped with an image forming apparatus, and usually, a paper cassette to load printable media such as individual cut sheets of paper. The paper loaded in the paper cassette is picked up and transmitted to a printer, and an image is printed onto one or both major surfaces of the paper with a dye such as a toner, and the paper is discharged from the apparatus.
Meanwhile, a paper jam sometimes occurs when printing the images on the paper. We have found that there are several reasons why the paper jam may have occurred. First, there is slippage of a pickup roller due to a difference of friction coefficients between the paper and the pickup roller. Therefore, the paper is not fed properly and a printing operation is not successfully performed. At this time, it is called a "Jam 0" or "feeding error".
Second, although the paper has been normally picked up, sometimes the apparatus fails to execute the feeding operation properly, a situation that is called a "Jam 1" or "transmission error". Third, when the printing operation is performed normally, but the operation of discharging the paper by conveying the paper through the apparatus and depositing the printed sheet of paper on a tray outside the apparatus is improperly executed, the occurrend is called a "Jam 2" or "discharging error".
As described above, when the paper jam occurs, the operation of the image forming apparatus must assume a standstill mode while waiting for the operator who is using the apparatus to correct the paper jam. In this state, since no keys on an operation panel can be operated by the user, the user has to first confirm the location of the paper jam, and the remove the jam, usually by removing the sheet of paper. We have also noticed that if a paper jam occurs in the image forming apparatus even though the paper has been properly loaded in the paper cassette, the paper will not be picked up, and all printing operations will be suspended until the user removes source of the error.